> anyone wanting a marriage license must produce a child within 6 months

So they start 3 months in advance? /s

Whatever, I think it's much easier to limit the number of children than to enforce a minimum. Both can be very unwelcomed for many reasons I don't want to get into, but not everybody can have children.

That's the point though, if the spouse cannot have a child, the marriage is annulled and the fertile partner gets a different spouse.

The idea is, "unwelcomed" is not an issue. In the Uighur regions, China is already practicing a form of marriage enforcement to make sure there's more han babies in the region.

Where are you getting this information from?

So couples will just... not marry?

You could theoretically levy an extra tax from childless people over certain age. That might work a bit in a non-democracy, where those people have no vote over their taxation levels.